1. Field of the Invention
The present invention relates to a toner for use in an electrophotographic method or a toner jet method.
2. Description of the Related Art
An electrophotographic method has been expected to satisfy various demands such as improvement in image quality, reductions in size and weight of an apparatus, attaining higher speed, and the reduction of energy consumption thereby, and an improvement in fixing performance of toner has been requested so as to satisfy those demands. In particular, an improvement in performance by which the toner can be fixed on a transfer material at a reduced temperature (hereinafter, referred to as “low-temperature fixability”) has been requested.
However, when the low-temperature fixability of the toner is improved, performance by which the occurrence of an image failure is suppressed in continuous printing after the toner has been stored under a high-temperature, high-humidity environment over a long time period (hereinafter, referred to as “durable stability”) is apt to reduce.
In a fixing step, performance by which offset as the following phenomenon is suppressed (hereinafter, referred to as “offset resistance”) is apt to reduce, because after the toner on the transfer material has adhered to a fixing member, the transfer material is contaminated by additional migration of the toner to the transfer material. In addition, performance by which the color-developing performance of an image is improved through the formation of a high-gloss image (hereinafter, referred to as “gloss performance”) and performance by which the occurrence of non-uniformity in the gloss of the image is suppressed (hereinafter, referred to as “penetration resistance”) are apt to reduce.
Accordingly, a toner that simultaneously satisfies the above performances has been demanded.
JP 2007-322499 A and JP 2008-58620 A each aim to achieve compatibility between the low-temperature fixability of toner and the improvement of the stability in continuous printing of the toner by coating a core particle having a low glass transition point (Tg) with a shell layer having a high Tg so that the exudation of the core particle to the surface of the toner during the storage of the toner may be suppressed.
JP 2007-225917 A aims to achieve compatibility between the low-temperature fixability of toner and the improvement of the stability in continuous printing by controlling a ratio between storage elastic moduli G′'s each serving as a rheology characteristic of a binder resin in the toner, the storage elastic moduli being obtained by performing dynamic viscoelasticity measurement for the toner at a temperature higher than the Tg of the binder resin by 35° C. and different frequencies.